This application focuses on Priority Area 5 of the RFA,"Chronic co-morbid conditions, such as obesity, cardiovascular disease, and diabetes." Due to successful treatment, men with hemophilia are living longer, more productive lives. However, many questions related to outcomes and co-morbidities and their management remain. While men with hemophilia were initially thought to be protected from cardiovascular disease, it is now clear that atherothrombotic events occur in this population. However, the prevalence of such events and the contributing risk factors are not clearly defined. The mainstay of treatment of cardiovascular disease (CVD) is antithrombotic therapy, which carries increased risks of bleeding in patients with hemophilia. We hypothesize that 1) CVD is present in the hemophilia population but less prevalent than found in the general U.S. population. We further hypothesize that 2) CVD risk factors are similar to those found in the general U.S. male population, but 3) patients with hemophilia are less likely to receive age- appropriate screening for CVD risk factors and 4) are at increased risk of bleeding complications related to antithrombotic treatment. To test these hypotheses we plan to utilize the American Thrombosis and Hemostasis Network (ATHN) of affiliate hemophilia treatment centers (HTCs) and data entry using the ATHN secure database in the following Specific Aims: 1) To determine the prevalence of cardiovascular disease in 200 male subjects with moderate or severe hemophilia A or B aged 54-73 years followed at HTCs;2) To compare prevalence data and CVD risk factors in subjects with hemophilia with male subjects in the ARIC database of the same age;3) To collect data on use and adverse events related to antithrombotic therapy in the 200 men;and 4) To determine the proportion of patients with hemophilia ages 35-54 years of age who have had recommended age appropriate screening for CVD risk factors. The results of these studies will provide important new data on CVD in hemophilia and its prevention and management. This should improve clinical care for this patient population as well as provide data on which to base future interventional and other studies in this population.